1. Field of the Invention
This invention relates to a strap assembly for carrying a load on one's shoulder wherein the assembly includes a padded shoulder strap secured to a functional sub-assembly having a plurality of straps comprised of elastic material and at least one strap of inelastic material. The plurality of elastic straps provide resistance to reduce the bouncing action of the load and consequent stress on the shoulder of the carrier. The elastic straps may be of variable length thereby providing graduated resistance to reduce the bouncing action over a range of load weights and conditions. The inelastic strap is the load bearing strap included to provide primary support for the load when the elastic straps have reached their maximum length.
2. Background of the Invention
One of the primary objectives of shoulder strap technology has been to minimize the stress that is transferred to the shoulder caused by the weight of the load. To minimize such stress on the shoulder, shoulder straps have typically included padding to absorb some of the shock of the load and also to distribute the load on the shoulder over a greater area of the shoulder for greater comfort. To reduce the bouncing action of the load, inventors have combined a totally resilient strap member with a non-stretchable strap member. The resilient strap member has served as both padding for the shoulder and as a shock absorber while the less resilient member has supported the load. This approach can be found in Coontz, U.S. Pat. No. 4,976,388, issued on Dec. 10, 1990 and in Heckerman, U.S. Pat. No. 4,827,578, issued on May 9, 1989.
One of the disadvantages of the prior art approach to the bouncing problem is that the resilient member typically has also served as the padding for the shoulder. This causes rubbing against the shoulder as the resilient member expands and contracts which can be a source of irritation. Additionally, the weight of the load has a tendency to stretch the resilient member to its maximum length and thus provides only limited protection from bouncing when the load is substantial.
Furthermore, when the resilient member has reached its maximum length, the weight of the load is born by the nonresilient or load bearing member. This is not a problem in itself. However, the load bearing member typically has been positioned above the resilient member. Hence, when the strap is in use, the resilient member is sandwiched between the shoulder and the load bearing strap. The force of the load bearing strap pressing the resilient strap against the shoulder can also interfere with the ability of the resilient strap to act as a shock absorber.
The present invention overcomes the problems in the prior art because the operational subassembly that dissipates the bouncing energy is not part of the padded member that comes in contact with the shoulder. Instead, the operational subassembly and padded shoulder strap member are positioned end to end. In this way, the resilient strap members do not come in contact with the shoulder. Therefore, the expansion and contraction of the resilient members do not rub against the shoulder. Furthermore, the load bearing strap does not trap the resilient strap members against the shoulder thereby allowing the resilient members to move freely in response to changing load forces.